In recent years, secondary batteries have been widely used not only for small-sized devices such as portable electronic devices but also for electric vehicles that require a driving force by using an internal combustion engine and/or an electric motor. The electric vehicle includes a hybrid vehicle, a plug-in hybrid vehicle, and a pure electric vehicle driven only by an electric motor and a battery without an internal combustion engine.
In an electric vehicle, a large number of secondary batteries are electrically connected to increase capacity and output. Particularly, pouch-type secondary batteries are commonly used in such medium or large devices since they are easily stackable on one another.
Since the pouch-type secondary battery is generally packaged by a battery case made of an aluminum and polymer resin laminate sheet and thus does not have great mechanical stiffness, when a battery module is constructed including a plurality of pouch-type secondary batteries, in many cases, cartridges are used in order to protect the secondary battery from external shock or the like, to prevent movement thereof and to facilitate easy stacking.
A plurality of cartridges accommodating the pouch-type secondary batteries are stacked on one another, and the battery module may be composed of the plurality of secondary batteries and cartridges stacked one another.
Meanwhile, a conventional cartridge is composed of a lower frame and an upper frame. For example, two secondary battery cells are stacked on an upper surface of the lower frame, then the upper frame is laid thereon, and then the upper and lower frames are coupled. Unit cartridges configured as above may be stacked up and down to form a cell cartridge assembly. If the cell cartridge assembly is prepared, a battery pack may be completed by assembling a sensing assembly connected to the plurality of secondary batteries to sense voltage characteristics of the secondary batteries and other electrical components such as BMS thereto.
However, in the conventional technique, any one unit cartridge should be assembled with another cartridge, and the assembled cartridges should be restrained using a fixing member to make a single body, which is a cumbersome manufacturing process. In addition, the cell cartridge assembly prepared as above should be assembled with other electrical components such as a sensing assembly, which requires housings and members for assembling them.
When manufacturing a battery pack as described above, if the number of assembling/coupling portions is increased, the manufacturing process becomes complicated, and the tolerance ratio may increase accordingly. In addition, the space occupied by other components in the battery pack is high in comparison to the space occupied by the secondary battery cells, which decreases the energy intensity and increases the manufacturing cost due to the increased number of components.